Publications de Manfred Schlosser

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The conversion of 2,2-difluoro-1,3-benzodioxole, an exceptionally acidic arene, via a 4-lithiated intermediate into more than three dozen new derivs. was conceived as a case study. The lithiated species was trapped by C0-electrophiles (4-toluenesulfonyl azide, fluorodimethoxyborane, iodine), C1-electrophiles (carbon dioxide, N,N-dimethylformamide, formaldehyde, di-Me sulfate), C2-electrophiles (oxalic acid diesters, oxirane), C3-electrophiles (oxetane), and higher alkyl iodides. The resulting carboxylic aci

Halogens, in particular fluorine atoms, are favorite tools to fine-tune the chemical and biological properties of pharmaceutical or agricultural development products. At the same time, such an electronegative substituent can effectively assist the site-sel ...

All twelve indolecarboxylic acids carrying both a fluorine substituent and a carboxy group at the benzo ring have been prepd. either directly from the corresponding fluoroindoles or from the chlorinated derivs. by hydrogen/metal permutation ("metalation"), ...

[on SciFinder (R)] ...

Fluorine leaves nobody indifferent; it inflames emotion, be that affections or aversions. As a substituent it is rarely boring, always good for a surprise, but often completely unpredictable. It behaves nonconformingly even when fundamental properties such as ionic dissocn. are under consideration. Although fluorine scores highest in the Pauling scale of electronegativity, its Hammett consts. (sm + 0.34, sp + 0.06) are all but spectacular. Alanine and a-fluoroalanine have virtually the same pKa values, wher

Long-range bonding interactions were evaluated using variable-temperature NMR spectroscopy and suitable 2'-CH2X-substituted phenylpyridines (X = Me, NMe2, OMe, F). It was found that the arylpyridyl rotational barriers were lower when electronegative atoms ...

A review. This review describes a concept aimed at rational and maximal structure proliferation. To this end, simple arom. or heterocyclic starting materials, often bulk chems., are converted into all regioisomerically possible polar organometallic interme ...

After alpha,alpha'-dimetalation, both 2,2'-diallyloxy-1,1'-binaphthyl and 2,2'-di-2-methylallyloxy-1,1'-binaphthyl undergo the Wittig rearrangement with perfect diastereoselectivity. When racemic 1,1'-binaphthyl-2,2'-diol ("BINOL") is used as the starting ...

The free energies of activation for the aryl-aryl rotation of 17 biphenyl derivatives, bearing a heavy heteroatom (S, Se, Te, P, Si, Sn) as ortho substituent, have been measured by variable temperature NMR. These numbers, so called B values, represent a me ...

The 2J (13C, H), a measure of bond angle in CH2:CHCH2R (R = MgBr, Li, Na, K), (Z)- and (E)-MeCH:CHCH2K, CH2:CHCH:CHCH2R (R = Li, K), or (E)-hexadienyllithium, is used to assign the % s character in the C-H bonds. This and the 13C NMR chem. shifts indicate conformations in which the cations are outside of the hydrocarbon planes and in which they participate in nonbonding interactions with every other (odd numbered) C atoms. The electrostatics, based on the electron d. in chains, are discussed. [on SciFinder

A -75 DegC, alpha-lithiated allyl Ph ether undergoes mainly the Wittig rearrangement to afford, after acidic hydrolysis, 1-phenyl-2-propen-1-ol as the main product. A second metalation taking place at one of the ortho positions is the sole competing side r ...

Torsional barriers of 15 ortho-substituted biphenyls have been determined computationally using the B3LYP density functional and experimentally by variable-temperature ("dynamic") nuclear magnetic resonance. Taking advantage of the 3'-isopropyldimethylsily ...

After treatment with an appropriate base (butyllithium or sodium amide), 2-alkenyltris(2-methoxymethoxyphenyl)phosphonium salts carrying an allyl, crotyl, or prenyl (3-methyl-2-butenyl) side chain condense with satd. or unsatd. aldehydes to give conjugated dienes with Z/E ratios ranging from 90:10 to > 99:1 and averaging 96:4. Owing to steric congestion, yields are only moderate (on av. 41%; extremes 10-79%). The nonvolatile tris(2-methoxymethoxyphenyl)phosphine oxide byproduct can be readily isolated and r

The relative basicities of aryllithiums bearing methoxy, chlorine, fluorine, trifluoromethyl and trifluoromethoxy substituents at the ortho, meta, and para positions have been assessed. To this end, two aryllithiums of comparable basicity were equilibrated ...

Trifluoromethoxy-substituted anilines undergo hydrogen/lithium permutation ("metalation") with optional site selectivity depending on the N-protective group employed. N-tert-Butoxycarbonyl-2- and -4-(trifluoromethoxy)aniline react with tert-BuLi at the nitrogen-adjacent 6- and 2-position affording, after electrophilic trapping, the corresponding substituted anilines I (R1 = F3CO, R2 = H, R3 = HO2C; R1 = H, R2 = F3CO, R3 = Me, CHO, HO2C, HOCH2CH2). In contrast, deprotonation of the N,N-bis(trimethylsilyl)-

The deprotonation energies of benzene, fluorobenzene, all di-, tri-, and tetrafluorobenzenes, pentafluorobenzene, chlorobenzene, all di-, tri-, and tetrachlorobenzenes, and pentachlorobenzene have been calcd. at various levels of second-order Moller-Plesse ...

N-Methyl-N-(2-propynyl)piperonylamine can be simultaneously lithiated at the terminal acetylenic and at that arom. position which is flanked by both the side chain and an oxygen atom. Under carefully established conditions, the metal occupying the latter ortho position can be selectively replaced by an electrophile. In general, it is however more convenient and also more efficacious to protect the acetylenic site by silylation. Then lithium may be introduced into the double-ortho position either by hydrogen

A systematic comparison between 1,3-difluorobenzene, 1,3-dichlorobenzene, and 1,3-dibromobenzene did not reveal major differences in their behavior towards strong bases such as lithium diisopropylamide or lithium 2,2,6,6-tetramethylpiperidide. Thus, all 2,6-dihalobenzoic acids are directly accessible by consecutive treatment with a suitable base and dry ice. In contrast, (2,6-dichlorophenyl)- and (2,6-bromophenyl)triethylsilane undergo deprotonation at the 5-position (affording the 4-carboxy derivs. and the

A deprotonation study was performed using 2,3,5-trichloropyridine, 3,5-dichloro-2-fluoropyridine, and 5-chloro-2,3-difluoropyridine as the substrates. Upon reaction with lithium diisopropylamide (LDA), deprotonation occurred exclusively at the 4-position. Subsequent carboxylation and iodination led to the acids and 4-iodopyridines. The exposure of the latter compds. to lithium 2,2,6,6-tetramethylpiperidide (LITMP) caused deprotonation and immediately ensuing iodine migration. The intermediates were trapped

Eight ethers, nine esters and one ketone were submitted to a systematic structural variation by replacing a hydrogen atom in the vicinity of the oxo function by fluorine and Me. As long as steric factors dominate, a fluorine substituent alters the olfactory properties of the parent compd. much less than a Me substituent does. However, if it occupies a position adjacent to a carbonyl group, the halogen may more profoundly affect the odor perception, presumably as a consequence of conformational changes. [on

Manfred Schlosser

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A homologous series of O- and N-functionalized 2,2-difluoro-1,3-benzodioxoles: An exercise in organometallic methodology

Position-flexible elaboration of halogenated heterocycles: Metalated species as key intermediates for synthesis

In search of simplicity and flexibility: a rational access to twelve fluoroindolecarboxylic acids

Alpha-fluorinated ethers, thioethers, and amines: anomerically biased species

Parametrization of substituents: effects of fluorine and other heteroatoms on OH, NH, and CH acidities

Long-Range Bonding/Nonbonding Interactions: A Donor Acceptor Resonance Studied by Dynamic NMR

The 2 * 3 toolbox of organometallic methods for regiochemically exhaustive functionalization

Embedding an Allylmetal Dimer in a Chiral Cavity: The Unprecedented Stereoselectivity of a Twofold Wittig [1,2]-Rearrangement

Rotational barriers of biphenyls having heavy heteroatoms as ortho-substituents: experimental and theoretical determination of steric effects

Nonplanar structures of allyl- and pentadienylmetal compounds: folding for better charge distribution?

Wittig rearrangement of lithiated allyl aryl ethers: a mechanistic study

B Values as a Sensitive Measure of Steric Effects

Bridging the final gap in stereocontrolled Wittig reactions: methoxymethoxy-armed allylic phosphorus ylides affording conjugated dienes with high cis selectivity

Relative Basicities of ortho-, meta-, and para-Substituted Aryllithiums

Trifluoromethoxy Substituted Anilines: Metalation as the Key Step for Structural Elaboration

The gas phase acidity of oligofluorobenzenes and oligochlorobenzenes: about the additivity or non-additivity of substituent effects

The organometallic route to benzylamine type monoamine oxidase inhibitors

Buttressing effects rerouting the deprotonation and functionalization of 1,3-dichloro- and 1,3-dibromobenzene

Regiochemical flexibility: the optional functionalization of 2,3,5-trihalopyridines at the 4- or 6-position

Odor-structure relationships using fluorine as a probe